The Operation of Draining Column Holdup for Slop Cut Withdrawal in Batch Distillation

The new mode of operation for slop cut withdrawal in batch distillation, i.e., draining Column liquid holdup at the end of slop cut period, was proposed. And the stopping criterion for the operation was investigated, Experiments were carded out with isopropanol-n-propanol binary system and isopropanol-n-propanol-n-butanol ternary system in a distillation column with a liquid collector installed between the reboiler and the column section, Experimental results in a Ф 45mm batch column show that the proposed policy can overcome the flywheel effect caused by column liquid holdup and thus cut down operation time and energy consumption 31%-61%.

Column Holdup Formula of Soil Solute Transport

The shortcomings of the present two formulae for describing column holdup are analyzed and deductions are made to find a new formula. The column holdup, Hw, described by the new formula is dimensional, and related to soil solute transport kinesis and column physical properties. Compared with the other two column holdups, Hw is feasible to describe dimensional column holdup during solute transport process. The relationships between Hw and retardation factor, R, in different solute transport boundary conditions are established.

The Operation of Draining Column Holdup for Slop Cut Withdrawal in Batch Distillation

The new mode of operation for slop cut withdrawal in batch distillation, i.e., draining column liquid holdup at the end of slop cut period, was proposed. And the stopping criterion for the operation was investigated. Experiments were carried out with isopropanol-n-propanol binary system and isopropanol-n-propanol-n-butanol ternary system in a distillation column with a liquid collector installed between the reboiler and the column section. Experimental results in a 45mm batch column show that the proposed policy can overcome the flywheel effect caused by column liquid holdup and thus cut down operation time and energy consumption 31%—61%.

Gas Holdups of Small and Large Bubbles in a Large-scale Bubble Column with Elevated Pressure

Gas holdups of large bubbles and small bubbles were measured by means of dynamic gas disengagement approach in the pressured bubble column with a diameter of 0.3 m and a height of 6.6 m. The effects of superficial gas velocity, liquid surface tension, liquid viscosity and system pressure on gas holdups of small bubbles and large bubbles were investigated. The holdup of large bubbles increases and the holdup of small bubbles decreases with an increase of liquid viscosity. Meanwhile, the holdup of large bubbles decreases with increasing the system pressure. A correlation for the holdup of small bubbles was obtained from the experimental data.

Bubble and Heat Transfer Phenomena in Viscous Slurry Bubble Column

Heat transfer and bubble phenomena were investigated by adopting the drift flux model in a viscous slurry bubble column reactor (SBCR), having a diameter of 0.0508 m(ID) and height 1.5 m. The effects of superficial gas velocity (0.002 -0.164 m/s), solid concentration (0 - 20 wt%) and liquid viscosity (paraffin oil;16.9 mPa•s and squalane;25.9 mPa•s) on the gas holdup and heat transfer characteristics were examined. It was observed that the gas holdup increased with increasing superficial gas velocity (UG), but decreased with increasing solid concentration (SC) or slurry viscosity. The degree of non-uniformity in a SBCR could be determined by the modified drift flux model at the heterogeneous flow regime. The local heat transfer coefficient (h) between the immersed heater and the bed decreased with increasing liquid viscosity and SC, but it increased with increasing UG. The modified Nusselt number including the gas holdup and local heat transfer coefficient was well correlated in terms of dimensionless groups such as Reynolds and Prandtl numbers.

Hydrodynamic Behavior in a Tapered Bubble Column

The experiment was conducted to explore the hydrodynamics in a conical column with a height of 3.00 m, and a taper angle of 1.91°. Three regimes occur in succession with increasing superficial gas velocity. Overall gas holdup increases with an increase in gas velocity and a decrease in solid concentration or static slurry height. Axial solid holdup becomes more uniform with increasing gas velocity, while axial gas holdup decreases from the bottom to the top. Both dry and wet pressure drops across the gas distributor increase with an increase in superficial gas velocity.

多孔板鼓泡塔流动与传质特性数值模拟

采用Euler-Euler双流体模型对安装不同数量的水平多孔板的鼓泡塔内气液两相流动及传质特性进行数值模拟研究,并探究了不同表观气速条件对鼓泡塔内气含率、气泡直径分布和气液传质系数的影响。结果表明,不同数量的多孔板和不同位置的多孔板都会影响气含率的分布;随着多孔板的数目增加,鼓泡塔液相上方区域的气含率增加,但影响区域有限;安装多孔板后,鼓泡塔内径向位置的平均气含率变化明显,出现“M”形状的分布。不同表观气速下,未安装多孔板的鼓泡塔内直径为1~2mm的微小气泡占比超过30%;安装多孔板后,微小气泡占比明显增加;气液传质系数在中心区域(径向无量纲为-0.5~0.5)较为平缓,波动不大。最后将模拟计算得到的气液体积传质系数与Akita的关联式计算值进行比较,本文计算结果略高。

泡沫分离过程中泡沫层总高度对持液率的影响

以乳链菌肽发酵液为模拟体系,研究了泡沫分离过程中泡沫层总高度对泡沫塔出口持液率εout以及泡沫层轴向持液率分布特性的影响。实验发现:在泡沫层形成过程中,εout从一个较低值逐渐升高到一个较高的稳定值;泡沫在塔内泡沫相中的停留时间不是εout的决定性因素,气速对εout的影响很大。同时还发现:随着泡沫层总高度的增加,εout缓慢下降而泡沫层与液层界面处的持液率急剧上升,可以推测出整个轴向持液率特性分布会上移。实验数据表明仅仅用静态泡沫的排液时间代替上升动态泡沫的停留时间的方法来预测εout的一般方法可能得出错误的结果。

加压大型气液鼓泡床中气含率的实验和关联

对内径0.3 m、高6.6 m的加压鼓泡床中的气含率进行了系统研究,得出了表面张力、粘度、压力等对气含率的影响规律;结果表明,在实验范围内,鼓泡床中的气含率随表面张力和粘度的升高而降低,随压力的升高而升高;并用气泡聚并的能量理论作了定性的解释. 根据542组实验数据得出了气含率的关联式.

浮选柱气含率及其影响因素对煤泥分选的研究

利用压差法检测浮选柱气含率,通过正交设计和煤泥浮选实验,研究循环压力、进气量和起泡剂浓度对气含率的影响以及气含率对煤泥浮选效果的影响.结果表明,起泡剂浓度对气含率的影响最大,进气量次之,循环压力最小.在一定范围内,随着气含率的增大,精煤产率增大,精煤的灰分也随之增大,精煤质量下降.当气含率为24.17%时,精煤产率为87.35%,精煤灰分为10.02%.随着循环压力增大,精煤产率增大,但精煤灰分有所下降.分析指出气含率大小可作为调节浮选柱矿物分选指标的一个参考标准.

混合溶剂间歇萃取精馏分离过程的模拟

由于混合溶剂存在"混合溶剂效应",能够解决简单溶剂选择性与互溶性相互矛盾的问题,因此混合溶剂间歇萃取精馏技术可以大大拓宽传统单一溶剂间歇萃取精馏分离技术的应用空间。文章建立了反映常规混合溶剂间歇萃取精馏过程的恒摩尔持液数学模型,并运用2点隐含法对其求解,结果表明,模拟计算结果与实验结果吻合较好。随后运用该模型探讨了塔身持液量、混合溶剂进料位置等因素对混合溶剂常规间歇萃取精馏的影响。得出以下结论,产品馏出速率随塔身持液量的增大而减小,塔顶馏分产量与塔身持液量的关系不大。另外,混合溶剂进料位置的选定对分离效果也有较大的影响,需要正确选择。

湍动浆态床流体力学研究(Ⅰ) 气含率及其分布规律

对高气速、高固含率、大塔径条件下的湍动浆态床平均气含率和气含率径向分布进行了实验测定,结合工业实验数据,归纳出可用于工业条件的气含率计算关联式,给出了简化的流体力学模型用于气含率分布的模拟。结果表明,浆态床气含率将随塔径增加而降低,固含率与塔径之间存在交互影响;同时,气含率的径向分布也随气速和塔径的增大而改变,存在明显的放大效应,简化模型能够较好地模拟实验结果。

泡沫相塔壁对泡沫分离牛血清蛋白分离性能的影响

为了强化泡沫排液,提出了泡沫相塔壁对泡沫分离性能影响的研究,为此设计了在泡沫相加内套筒的泡沫分离塔,以牛血清蛋白(BSA)为研究体系,研究泡沫相塔壁对出口持液量、气泡大小、富集比和回收率的影响,从而研究这种泡沫分离塔的泡沫分离性能。结果表明与没有加内套筒的对照塔相比,加内套筒的实验塔降低了持液量,加速了泡沫的变大和聚并,提高了BSA富集比。在400ml.min-1气速下,BSA初始浓度为0.2g.L-1时,实验塔的富集比是对照塔BSA富集比的2.06倍。BSA富集比随着加入内套筒长度的增加而增加。实验塔取得较好的泡沫分离性能表明了塔壁处的普拉特边界排液量大于气泡间的普拉特边界排液量,内套筒的加入增加了塔壁的普拉特边界数量,起到了强化排液的作用。

鼓泡塔反应器的两级气泡模型参数研究

为了研究鼓泡塔反应器两级气泡模型在高黏度下的适用性,采用动态气体逸出法,在内径为286 mm,总高为7 200 mm的鼓泡塔中考察了液体黏度(1.2×10-3—210.4×10-3Pa·s)和操作条件对塔内总气含率,大、小气泡相含率和大、小气泡上升速度等两级气泡模型参数的影响。结果表明:床层总气含率随表观气速的增加而增大,大气泡相含率受液体黏度的影响较小,受表观气速的影响较大;小气泡相含率随黏度的增加而迅速下降,在高气速时受表观气速的影响较小。大、小气泡上升速度均随液体黏度的增加而降低,但随表观气速的升高有着不同的变化关系:前者明显升高,后者略有降低。大气泡直径随着黏度增大而稍有增大,小气泡直径随着黏度增大急剧减小。

用神经网络法预测鼓泡塔内的气含率

在 2 0 0 0多组公开发表的鼓泡塔实验数据组成的数据库基础上 ,提出了一个预测鼓泡塔内气含率的关联式 ,介绍了一种新的神经网络回归方法。将该方法与受力分析结合起来得到 4个对鼓泡塔内气含率影响较大的无因次准数 。

喷管分布器大型浆态鼓泡床反应器气含率的研究

采用内径0 284m、高3m的浆态鼓泡反应器,研究液体流速、分布器形式、高径比、固体质量分数及颗粒粒径大小等因素对反应器内气含率及气泡大小的影响规律。实验结果表明,气含率随体系内固相浓度增加和颗粒粒径的增大而减小,大气泡含率随表观气速、固相浓度增加和颗粒粒径增大而增大,液体逆流、静液高度及分布器形式对气含率无影响。并得出气含率的关联式。

加压浆态鼓泡床中固含率与气含率轴向分布的研究

在高6.6 m、直径0.3 m的浆态鼓泡塔中,采用动态气体逸出法研究了水-空气-石英砂体系中固含率与气含率的轴向分布。在表观气速0-0.24 m/s、固体质量分数(石英砂在水中的质量分数)0-23％、压力0.1-2.0 MPa范围内,考察了各种因素对固含率和气含率轴向分布的影响。实验结果表明,随着表观气速的增加和固体质量分数的减小,固含率的轴向分布趋于均匀;气含率随压力和表观气速的升高而增加;固体质量分数仅仅影响大气泡气含率和上升速率,而对小气泡气含率和上升速率的影响不大;在固体质量分数大于23％时,压力对气含率轴向分布的影响比较显著。

搅拌萃取塔液泛速度和滞存率的研究

在内径为 90 mm的搅拌萃取塔中 ,对分散相滞存率和液泛速度进行了研究 .实验用的物系为煤油 -水、煤油 - 15 %甘油水、锭子油 -水、2 -乙基己醇 -水 .实验结果表明 :转速、相比、物性对液泛速度、滞存率都有影响 ,而且在较低能耗下搅拌萃取塔处理界面张力大的物系时显示出较大优越性 .同时 ,利用因次分析法 。

压降法测量往复振动筛板萃取柱内分散相的滞存率

本文从理论上建立了往复振动筛板萃取柱内分散相总体平均滞存率与压降的关系，测量了各种操作条件下柱内分散相的总体平均滞存率，为开展往复振动筛板萃取柱内两相流动与传质行为的研究提供了基础。

旋流喷射浮选柱气含率影响因素研究

浮选柱气含率大小是决定浮选效果的一个很重要的因素。研究了清水且不加起泡剂的条件下旋流喷射浮选柱中静压力大小、流体流量和充气量对气含率的影响以及挡板添加时气含率的变化情况。结果表明:气含率随着流体静压力、流体流量以及充气量的增加而增大,并且流体流量的影响最大,静压力的影响最小。在添加挡板的情况下,气含率随着挡板高度的增加以及离矿浆喷射端口距离的增加而增大,要得到合适的气含率,所加挡板的高度应高于柱体总高度的2/10,同时挡板离喷射端口的距离应控制在柱体长度的5/10和7/10之间。